One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(14,18)(15,21)(16,23)(20,24)(22,25)(26,28) involution — undirected(2,4)(5,6,8,9)(7,10,11,12)(13,14,17,20)(15,19,22,27)(16,24,23,18)(21,26,25,28)(6,9)(7,11)(13,15,17,22)(14,19,20,27)(16,25,23,21)(18,26,24,28)(5,7)(6,10)(8,11)(9,12)(14,20)(18,24)(19,27)(26,28) involution — undirected(6,9)(7,11)(14,20)(18,24)(19,27)(26,28) involution — undirectedA Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.